diff --git a/Data-Structure.md b/Data-Structure.md
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--- a/Data-Structure.md
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-# Giti Data Structure
-
-## ID
-- To have canonical data structure IDs calculate it from hash of URN.
-- ID is first 64bit of SHA-512 hash of data structure URN!
-- Zero ID means no data structure!
-
-## URN
-`urn:giti:{{domain-name}}:data-structure:{{data-store-name}}`
diff --git a/Error.md b/Error.md
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-# Giti Error
-
-## ID
-- To have canonical error IDs calculate it from hash of URN.
-- ID is first 64bit of SHA-512 hash of error URN!
-- Zero ID means no error!
-
-## URN
-`urn:giti:{{domain-name}}:error:{{error-name}}`
diff --git a/Service.md b/Service.md
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-# Giti Service
-
-
-## ID
-- To have canonical error IDs calculate it from hash of URN.
-- ID is first 64bit of SHA-512 hash of service URN!
-- Zero ID means no service!
-
-## URN
-`urn:giti:{{domain-name}}:service:{{service-name}}`
diff --git a/media-type.md b/media-type.md
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+## Media Type Extension
+Want a protocol to declare global service, error, ... in any language with desire goals, So we decide to add new main-type to media-type URI scheme instead invent from scratch. Add new top-level type names (main-type) as `domain` instead of `application` to have proper way to indicate domain specific media types.
+
+## Structure
+`type "/" [tree "."] subtype ["+" suffix]* [";" parameters]`   
+`domain/{{domain-name}}. {{structure-type}} +{{codec-type}} ;{{structure-name}}`   
+`domain/sabz.city.storage+syllab; quiddity`
+- **domain-name** as a tree for a organization by its domain name.
+- **structure-type** or structure scope like `storage`, `service`, `error`, `page`, `widget`, ...
+- **codec-type** like `syllab`, `json`, `xml`, `protobuf`, `flatbuf`, `html`, ...
+- **structure-name** must be unique in the domain scope e.g. "product" in the "page" scope of the domain. e.g. `log`, `get-email`, `get-email`, `request`, `response`, `not-standard-structure-id`, ... Due to RFC rules, a media-type can has more than one parameters, so you can easily add more than one if need it like http that use `charset=` and `boundary=` in content-type header.
+
+## ID
+- To have canonical structure IDs calculate it from hash of MediaType().
+- ID is first 64bit of SHA3-256 hash of structure that transfer in base64 if protocol is string base.
+- Zero ID means no data structure e.g. no error, ....
+
+## Goals
+- Easily generate SDK in any programing language
+- Transfer and retrieve by ID in any protocol
+- Store locale detail not just english detail
+- 
+
+## Other ways
+- use URN standard like `urn:giti:sabz.city:page:login` as `urn:giti:{{domain-name}}:{{structure-type}}:{{structure-name}}`
+
+## RFCs
+- https://datatracker.ietf.org/doc/html/rfc6838
+- https://datatracker.ietf.org/doc/html/rfc2046
+- https://datatracker.ietf.org/doc/html/rfc2609
+
+## Resources
+- https://en.wikipedia.org/wiki/Media_type